1. Field of the Invention
This invention is concerned with the catalytic dehydrogenation of p-ethyltoluene to p-methylstyrene. It is more particularly concerned with the prevention of polymer formation by the effluent gases in the condenser or cooling train.
2. Description of the Prior Art
It has been proposed to inhibit polymerization by adding various materials to vinyl aromatics being purified by distillation. Typical additives include nitrosoanilines, nitro and halo nitro substituted cresols, and halo nitrotoluene. Note, for example, U.S. Pat. Nos. 4,050,993; 4,086,147; 4,132,602; and 4,132,603. Insofar as is now known, it has not been proposed to prevent polymer formation in the cooling train by adding H.sub.2 S to the effluent from the catalytic dehydrogenation of p-ethyltoluene.